UK has proportionally more violent crime than the US. However it has vanishingly fewer murders (again proportionally to population).
Stabbings between schoolkids are getting a lot of publicity in the UK just now. Personally I think a lot of that is media-driven - not by imitation but by an environment of fear. If you're constantly told that the kids at other schools have knives, you're more likely to want one yourself for protection. Or, worse, you might up the ante and find a gun.
I'm with dianavan on this one. If you get in a punch-up with someone, you're unlikely to die. If guns or knives are involved, you *are* likely to die. If you're in a fight, you're not going to be sporting and avoid using a knife just because your opponent hasn't (or hasn't *yet*) - if you carry a weapon, eventually it'll get used.
Incidentally, when people wring their hands about violent crime these days and how things were better in the "old days", I always want to know when those "old days" were. Look back 50 years and you've got punks, skinheads, Mods, Rockers and Teds, just to name the most obvious ones. And the infamous English football hooliganism of the 70s and 80s. And the Afro-Caribbean immigrant community (a quote I heard from a radio documentary about the old dancehalls and sound systems was: "A white guy only had to know one person to get in, but he'd have to know the whole hall to get out").